Electronic components mounted on circuit boards generate heat that must be dissipated to assure proper functioning of the components. Air is typically used to cool the circuit board when the total power dissipated is low or when the power density is low. In high power applications, liquid can be used to provide significantly improved cooling, but at an added level of complexity. The liquid must be contained so it does not contact the components directly.
A way to contain cooling liquid is to use a liquid-cooled cold plate, typically made of copper, aluminum, or alloys thereof. The cold plate has channels within it that distribute the cooling liquid and has inlets and outlets that enable the liquid to enter and exit the cold plate. The cold plate is mated to the electronic circuit board that requires cooling. Electrical components on the circuit board are cooled by contact with the cold plate such that heat is transferred from the components to the cooling fluid.
In a typical manufacturing technique for creating high performance vacuum-brazed cold plates, a channel is machined in a metal plate, typically a ½ inch to 1½ inch thick aluminum plate. The channel is filled with a plurality of fins formed in a custom stamping operation to provide a large surface area for the heat transfer function. A cover plate is added to the top, and the whole assembly is vacuum-brazed together. Fluid inlet and outlet fittings are attached at suitable locations, such as along the edge of the cold plate, to deliver fluid into and out of the channel.